ARLINGTON — The sun was going down and the river ran red.
It wasn’t the reflection of the sunset, however.
Earlier this week, state Department of Ecology researchers Markus Von Prause and Ralph Svrjcek waded out hip-deep into the Stillaguamish to pour fluorescent red dye into the river as part of water quality study.
Fluorometers activated throughout the night measured the concentration of the dye in a dozen locations from Haller Park in Arlington downstream about six miles to I-5. The monitors collected data about river travel times, temperature, oxygen levels and how fast the dye, representing pollution, dissipated in the river.
The dye doesn’t harm people, fish or wildlife, but Svrjcek and Von Prause wore gloves as they placed the dye in the Stilly. Sunbathers along the river’s edge had gone home and the river was quiet.
The Stillaguamish River has a shortage of oxygen in some places in the area, making it difficult for fish, such as chinook salmon fry, to survive. Too much nutrient pollution, like phosphorus and nitrogen, leads to oxygen shortages, Svrjcek said.
The research gathered from the dye test won’t be available for several months. The results should help Ecology update its 2007 water-quality improvement plan, which guides efforts to control sources of pollutants in the Stillaguamish watershed, Ecology officials said.
Since the last study, the city of Arlington has built a state-of-the-art sewer treatment plant and is even cleaning up its stormwater before letting it run into the river.
Recent tests have shown that what the city discharges into the river is cleaner than what it takes out at its treatment plant to provide water to people in Arlington, said James Kelly, public works director for the city.
Pollution could come from a variety of other sources in the area, including groundwater, Svrjcek said.
“The dye test is just one of many that the state patches together to form a complicated picture of the health of the river,” he said. “One weak link can create problems for fish. Our goal is healthy fish in a healthy river.”
More information is available at tinyurl.com/doeStilly.
Gale Fiege: 425-339-3427; firstname.lastname@example.org.